1. Field of the Invention
The present invention relates generally to sheet feeding devices and image recording apparatuses with sheet feeding devices comprising a plurality of sheet cassettes, and more particularly to the image recording apparatuses configured to readily clear sheet jams that may occur when sheets are fed from the sheet cassettes.
2. Description of Related Art
A known image recording apparatus, e.g., a copier and a printer, includes an upper sheet cassette and a lower sheet cassette that are independently inserted into or removed from a housing of the apparatus. The known image recording apparatus includes a recording unit positioned above the upper sheet cassette. A U-shaped sheet path is positioned on a rear side of the known apparatus with respect to a cassette insertion and removal direction. Another known image recording apparatus, e.g., the image recording apparatus described in Japanese Laid-Open Patent Publication No. 2006-103954 or corresponding U.S. Pat. No. 7,553,012 B2, includes a feeding device positioned in a housing of the apparatus.
The known image recording apparatus includes a first U-shaped sheet path for feeding a sheet fed from the upper sheet cassette upward while turning the sheet upside down and a second U-shaped sheet path for feeding a sheet fed from the lower sheet cassette upward while turning the sheet upside down. The first and second sheet paths merge into one sheet path leading toward a registration rollers.
The second sheet path is positioned outside of a curvature of the first sheet path. The second sheet path is defined between an inner surface of a second guide member, which is positioned on a rear portion of the housing, and an outer surface of a first guide member. The first guide member and the second guide member are connected to each other to form a guide unit. The guide unit is detachably attached to the rear portion of the housing. The first sheet path is defined between an inner surface of the first guide member and an outer surface of a third guide member. The third guide member is fixed to a main frame of the housing.
The guide unit is removed from the rear portion to clear sheet jams occurred in the first or second sheet path. The first and the second feed guide members are connected to each other, so that it is sometimes difficult to clear sheet jams occurred in the second sheet path. Especially, in a state in which the leading end of a sheet passing through the second sheet path is held between the registration rollers and the trailing end of the sheet is pressed against the pickup roller, a portion of the sheet positioned in a curved portion of the second sheet path may be damaged when the guide unit is removed from the rear portion. Thus, sheet jams cannot be readily cleared.
Another known image recording apparatus, e.g., the image recording apparatus described in Japanese Laid-Open Patent Publication No. 11-272144, includes an image forming unit positioned in a middle portion of a housing with respect to a vertical direction. The another known image forming unit includes a photosensitive member, a toner transfer portion, and a thermal fixing portion. Two sheet cassettes are arranged in a vertical direction below the image forming unit. The another known image recording apparatus includes a U-shaped second sheet path through which a sheet output from the thermal fixing portion is fed toward an output tray positioned on an upper portion of the housing, and a first sheet path configured to feed a sheet in a direction to opposite to the second sheet path. A path switching mechanism including two switching members is positioned at a branching point of the first and second sheet paths.
An output opening and output rollers are positioned at an end of the second sheet path. When a sheet is fed toward the output opening and its trailing end reaches between the output opening and one of the switching members, the output rollers are reversely rotated to change states or positions of the switching members. The sheet having a recorded image on its surface is reversely fed toward the first sheet path and passes through the image forming unit again. The image forming unit forms an image on an opposite, e.g., rear, side of the sheet. The double-sided recorded sheet is output to the output tray through the second sheet path.
A second cover defining the second sheet path is positioned higher than a first cover defining the first sheet path. The image recording apparatus includes an operative mechanism configured to open the first cover in association with an operation of opening the second cover. The first and second covers both need to be open to clear a sheet jam because it is difficult to judge whether a sheet jam occurs in the first or the second sheet path.
Further, in the structure in which the first and the second sheet paths are formed almost at the same height, if the first and second guide members are configured to pivot about a lower end of each first and second guide member and if sheet jams occur in the second sheet path, the sheet is damaged while clearing the sheet jam, because when the first and second guide members are both open at the same time, the sheet in the second sheet path is pressed by the first guide member. To prevent damage to the sheet, the first and second guide members need to be separately open, which is inconvenient and time-consuming. Further, after clearing the sheet jam, the guide members need to be separately returned to their original positions.